I ran mine 24 hours a day for the first two weeks. It is a good idea to run it this long in order to pick up the plaster dust which, if your not careful, can solidify on the surface making it very rough. Make sure you brush at least once a day and move all of the dust toward the main drain so the filter can remove it. Brushing the sides and bottom makes the plaster very smooth so the more you can do it, the better.